Dentin – Oral Histology · FCPS Part 1

Types

Dentin Type	Developmental Classification	Key Histological Features	High-Yield MCQ Triggers
1. Mantle Dentin	Primary Dentin	* The very first layer of dentin formed. * Located right beneath the DEJ. * Contains thick von Korff’s fibers (Type III collagen).	* "First-formed dentin". * Slightly less mineralized than circumpulpal dentin. * Does not contain phosphophoryn.
2. Circumpulpal Dentin	Primary Dentin	* Forms the remaining bulk of the primary tooth structure. * Contains smaller collagen fibers running perpendicular to tubules.	* Forms the bulk of the tooth before eruption is complete.
3. Secondary Dentin	Secondary Dentin	* Formed after root completion and when the tooth is in occlusion. * Deposited at a much slower, continuous rate throughout life.	* Causes the pulp chamber to shrink/recede with age. * Has a regular tubule pattern, though slightly asymmetrical compared to primary dentin.
4. Tertiary (Reparative) Dentin	Tertiary Dentin	* Formed rapidly in response to localized injury (caries, attrition, trauma). * Deposited only by odontoblasts directly affected by the stimulus.	* "Reactionary" or "Reparative" dentin. * Characterized by a highly irregular, atubular (few or no tubules) or distorted appearance.
5. Intratubular (Peritubular) Dentin	Structural Classification	* Forms the wall/lining inside each dentinal tubule. * Highly mineralized (more than intertubular dentin).	* "Continuously produced throughout life" (Answer to Q17). * Its continuous deposition leads to tubule obliteration (Sclerotic dentin).
6. Intertubular Dentin	Structural Classification	* Located between the dentinal tubules. * Consists of a tightly woven network of Type I collagen fibers.	* Represents the primary structural framework or network of the dentin body.
7. Interglobular Dentin	Mineralization Defect	* Unmineralized or hypomineralized pockets where globular calcification centers failed to fuse.	* "Hypomineralized areas". * The dentinal tubules run completely uninterrupted through these spaces (a major MCQ true/false trap!).